Nowadays, lively researches and developments in various display devices are being made. Of such devices, the organic electric-field luminescent (EL) devices are receiving particular attention as promising display devices because they can emit light of high intensity under low voltage. For instance, the Light emitting devices having organic thin films formed by vapor deposition of organic compounds are known (Applied Physics Letters, 51, p. 913 (1987). The organic Light emitting devices described in the literature cited above employ tris (8-hydroxyquinolinato) aluminum complex (Alq) as an electron transporting material and is structured to superimpose a layer of positive hole transporting material (an amine compound) on the layer of electron transporting material, and thereby show substantial improvements in their luminescent (light emitting) characteristics over conventional single-layer devices.
In recent years, the application of organic EL devices to full-color display has been examined actively. In order to develop high-performance full-color display, it is necessary to improve on the characteristics of conventional blue, green and red light emitting devices respectively. As to the blue light emitting devices, for instance, the distyrylarylene compounds (DPVBi) described in a book entitled “Organic EL devices and Forefront of Industrialization thereof”, at page 38 (published by NTS Co.) have been studied extensively, but they have problems with color purity, durability, luminous intensity and efficiency, and so further improvements in these characteristics have been expected.
Although the organic light emitting devices comprising organic materials laminated by vacuum evaporation have really succeeded in luminescence (light emitting) of high luminance, the use of coating methods for manufacturing devices have advantages over that of vacuum evaporation methods from the viewpoints of simplicity of the manufacturing process, workability and ease in achievement of large-area luminescence. However, the devices, especially blue light emitting devices, manufactured according to conventional coating methods are inferior to those manufactured using vapor deposition methods in luminous intensity and luminous efficiency. Therefore, the development of novel blue luminescent materials has been awaited.